Physical activity slows cognitive decline, regardless of tau levels

Physical activity correlated with slower cognitive decline among people with both high and low tau concentrations, according to a population-based cohort study in JAMA Network Open.

“A lengthy preclinical [Alzheimer’s disease] phase offers the chance for intervention, such as engagement in physical activity or increasing adherence to physical activity, to positively impact the disease before clinical symptom onset,” Pankaja Desai, PhD, assistant professor at Rush University Medical Center’s Institute for Healthy Aging in Chicago, and colleagues wrote. “However, limited work has been done to understand the association of physical activity and total tau concentrations with cognitive decline.”

Researchers collected data from 1,159 participants (63% women; 60% Black) aged older than 65 years (mean age, 77.4 years) without AD living in 4 Chicago communities. Data collection occurred in 3-year cycles from 1993 to 2012.

Participants provided information through in-home interviews and clinical evaluations, including blood samples to analyze total tau levels at baseline, and self-reported physical activity. Researchers assessed cognitive function through the East Boston Tests of Immediate Memory and Delayed Recall, the Mini-Mental State Examination and the Symbol Digit Modalities Test.

Low physical activity at baseline correlated with lower cognitive function scores than less than 150 minutes (medium physical activity) or at least 150 minutes (high physical activity) of physical activity each week.

In participants with high tau levels, medium activity correlated with a 58% slower rate of cognitive decline (estimate, 0.028 standard deviation units [SDU] per year; 95% CI, 0.057 to 0.002 SDU per year) than little activity (0.066 SDU per year; 95% CI, 0.097 to 0.034 SDU per year). The researchers linked high activity to 41% slower decline (0.038 SDU per year; 95% CI, 0.068 to 0.009 SDU per year).

Among those with low tau levels, medium physical activity was tied to a 2% slower rate of cognitive decline (–0.05 SDU per year; 95% CI, –0.069 to –0.031 SDU per year) compared with little activity (–0.051 SDU per year; 95% CI, –0.072 to –0.029 SDU per year). High physical activity correlated with a 27% slower decline (–0.037 SDU per year; 95% CI, –0.055 to –0.019 SDU per year) among those with low tau levels.

Individual tests of cognitive function demonstrated similar findings, according to the researchers.

Limitations included unclear cutoffs for biomarker measurements, self-reported physical activity and selection bias, while the study’s biracial sample represented a strength. Future studies may look more closely at activity type and other health behaviors, according to the researchers.

“These results suggest that physical activity may have a positive association with cognitive function and that sedentary behavior may have a negative association with cognitive function,” Desai and colleagues wrote.